I am having a problem when I am about to stop in traffic. The engine shakes and it feels as if the idling speed suddenly goes down and the engine would stall when I step on the brakes . A couple of times it did stall and a couple of times , it recovered and went back to its normalidling speed. I thought it was the battery or alternator but the battery is new and the repair shop did a diagnostic and they found nothing wrong with the alternatorand no fail codes showed up.It is getting to be annoying. I really need to get some input so i might ask the shop to check some other things that may be causing this problem. Thanks in advance.